Glass parts and gob-pressing methods for making such

A method of making a glass part, comprising:

• gob-pressing glass to form the glass part, wherein the gob-pressing comprises pressing a gob of molten glass with a piston into a mold such that the gob spreads outward in the mold to form the molten glass to a shape of the glass part,
• wherein the shape comprises first and second major surfaces facing away from one another and a thickness orthogonal to the first and second major surfaces and extending therebetween, and wherein the shape has length and width aligned with the major surfaces and orthogonal to one another;
• wherein the first and second major surfaces each have an area of at least 4 cm2 and the thickness is less than 2 mm for at least a portion of the shape between the major surfaces;
• wherein a cross-sectional portion of the shape between the first and second surfaces extending along a 2 cm linear path varies in thickness less than 100 μm;
• wherein the thickness for the portion of the shape is a first thickness and wherein the shape comprises a second thickness that is at least twice the first thickness;
• wherein the shape comprises a side wall positioned on a periphery of the shape;
• wherein the side wall extends at least 2 mm normal to at least a portion of the first and second major surfaces;
• wherein the glass of the glass part is an aluminosilicate, comprising in molar percentage on an oxide basis at least 40 mol % silica and no more than 80 mol % silica, and at least 2 mol % alumina and no more than 20 mol % alumina;
• wherein the glass is configured for chemical strengthening, comprising at least 5 mol % alkali metal oxides and no more than 25 mol % of the alkali metal oxides;
• wherein the glass has an average total transmission of greater than 40% between wavelengths of 450 nm and 650 nm fully through the thickness of at least a portion of the glass part;
• and
• heat treating the glass, subsequent to the gob-pressing, to grow crystals therein;
• wherein the crystals are distributed within the glass of the glass part, and wherein a volume percent of crystals is less than 95% of the glass part;
• and
• wherein the fracture toughness of the glass part is 1.0 MPa·m1/2 or more.

A method of making a glass part, comprising:

• gob-pressing glass to form the glass part, wherein the gob-pressing comprises pressing a gob of molten glass with a piston into a mold such that the gob spreads outward in the mold to form the molten glass to a shape of the glass part,
• wherein the shape comprises first and second major surfaces facing away from one another and a thickness orthogonal to the first and second major surfaces and extending therebetween, wherein the shape comprises a geometric centroid, and wherein the shape has length and width aligned with the first and second major surfaces and orthogonal to one another;
• wherein the first and second major surfaces each have an area of at least 4 cm2 and the thickness for at least a portion of the shape between the major surfaces is less than 2 mm;
• wherein the thickness for the portion of the shape is a first thickness and wherein the shape comprises a second thickness that is greater than the first thickness;
• wherein the second thickness is located at least 1 cm away from the geometric centroid;
• wherein a cross-sectional potion of the shape between the first and second major surfaces extending along a 2 cm linear path varies in thickness less than 100 μm;
• wherein the shape comprises curvature of at least a portion of surfaces thereof that comprises a radius of curvature of less than 1 m;
• wherein the length of the shape is greater than the width;
• wherein the glass of the glass part is an aluminosilicate, comprising in molar percentage on an oxide basis at least 40 mol % silica and no more than 80 mol % silica, and at least 2 mol % alumina and no more than 30 mol % alumina;
• wherein the glass has a dielectric constant Dk at 10 GHz less than or equal to 6.8;
• wherein the glass comprises a colorant selected from the group consisting of Au, Ag, Cr2O3, transition metal oxides, and rare earth metal oxides;
• wherein the glass further comprises transmittance through at least a portion of the thickness with color coordinate in CIELAB color space of L* greater than or equal to 55 and less than or equal to 98.5, a* greater than or equal to −10 and less than or equal to 25, and b* greater than or equal to −20 and less than or equal to 5 under F2 illumination and a 10° standard observer angle;
• and
• heat treating the glass of the glass part to grow crystals therein, wherein the crystals comprise lithium disilicate.

A method of making a glass part, comprising:

• gob-pressing glass to form the glass-part, wherein the gob-pressing comprises pressing a gob of molten glass with a piston into a mold such that the gob spreads outward in the mold to form the molten glass to a shape of the glass part,
• wherein during at least a portion of the gob-pressing, the glass comprises a viscosity less than 1200 poise;
• wherein the shape comprises first and second major surfaces facing away from one another and a thickness orthogonal to the first and second major surfaces and extending therebetween,
• wherein the shape comprises a geometric centroid, and
• wherein the shape has a length and width aligned with the first and second major surfaces and orthogonal to one another;
• wherein the first and second major surfaces each have an area of at least 4 cm2 and the thickness for at least a portion of the shape between the major surfaces is less than 2 mm;
• wherein the thickness for the portion of the shape is a first thickness and wherein the shape comprises a second thickness that is greater than the first thickness;
• wherein the second thickness is located at least 1 cm away from the geometric centroid;
• wherein a cross-sectional portion of the shape between the first and second major surfaces and extending along a 2 cm linear path varies in thickness less than 100 μm;
• wherein the shape comprises a curvature of at least a portion of surfaces thereof that comprises a radius of curvature of less than 1 m;
• wherein the length of the shape is greater than the width;
• wherein the glass of the glass part is an aluminosilicate, comprising in molar percentage on an oxide basis at least 40 mol % silica and no more than 80 mol % silica, and at least 2 mol % alumina and no more than 30 mol % alumina;
• wherein the glass has a dielectric constant Dk at 10 GHz less than or equal to 6.8;
• wherein the glass is configured for chemical strengthening, comprising at least 5 mol % alkali metal oxides and no more than 25 mol % of the alkali metal oxides;
• chemically strengthening the glass of the glass part, wherein the glass has a surface compressive stress and a central tension;
• and
• heat treating the glass of the glass part to grow crystals therein, wherein the crystals comprise at least 50 vol % of the glass part and no more than 99 vol %.